NEW YORK – In yet another change that upset users, Facebook has replaced the email addresses users chose to display on their profile pages with (at)facebook.com addresses.

Previously, users may have displayed their personal yahoo.com or gmail.com address to let people know how to contact them outside of Facebook. Now, Facebook has hidden those addresses and put a Facebook email listing in its place.

The changes raised users' suspicions. By hiding other email addresses Facebook can keep its already-captive audience even more captive. Sending an email to a Facebook.com address will land the email in the messages section of a user's Facebook profile. The more people use Facebook to communicate, the more the company can target ads based on the conversations they have on its platform —just as Google targets ads to Gmail users based on text in their emails.